December 10, 2019

Next batch of Planet’s upgraded Earth-imaging satellites ready for launch


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One of Planet’s SkySat satellites captured this view of a launch pad at the Satish Dhawan Space Center in India. Credit: Planet

A dozen SuperDove nanosatellites with improved vision are set to join Planet’s Earth-observing fleet Tuesday night (U.S. time) after riding into orbit aboard an Indian Polar Satellite Launch Vehicle alongside an Indian mapping payload.

The 12 SuperDove satellites will lift off on India’s PSLV at 10:58 p.m. EST Tuesday (0358 GMT Wednesday) from the Satish Dhawan Space Center, located on Sriharikota Island on India’s southeastern coast.

The primary payload on the PSLV flight is Cartosat 3, a new Earth-imaging craft built and owned by the Indian Space Research Organization, the Indian space agency which also oversees PSLV launch operations at Sriharikota.

The PSLV will fire off the Second Launch Pad at Sriharikota, the newer of two launch facilities at the seaside rocket base. The launch is scheduled for 9:28 a.m. local time in India.

A solid-fueled core stage and four strap-on solid rocket boosters will propel the 144-foot-tall (44.4-meter) PSLV off the launch pad with up to 1.7 million pounds of thrust.

The PSLV will initially heard southeast from the Satish Dhawan Space Center over the Bay of Bengal, then turn south a few minutes after liftoff. The so-called “dogleg” maneuver will ensure the PSLV does not fly over populated areas of Sri Lanka.

Four of the PSLV’s side-mounted boosters will ignite at liftoff to help push the rocket off the launch pad. Two additional boosters will fire at T+plus 25 seconds to provide an extra burst of energy.

The first four boosters will burn out and jettison at T+plus 1 minute, 10 seconds, followed by burnout and separation of the other two solid rocket motors at T+plus 1 minute, 32 seconds.

The PSLV’s core stage motor, designated the PS1, will consume its pre-packed solid propellant before burning out and separating at T+plus 1 minute, 53 seconds. The PSLV’s second stage, powered by a hydrazine-fueled Vikas engine, will ignite at the same time to begin a two-and-a-half minute firing.

The rocket will release its nose cone at T+plus 2 minutes, 36 seconds, at an altitude of nearly 380,000 feet (116 kilometers) after climbing above the thick, lower layers of the atmosphere. The payload shroud protects the rocket’s satellite passengers during the first few minutes of flight.

An Indian Polar Satellite Launch Vehicle rolls out of an assembly building at the Satish Dhawan Space Center in preparation for launch with the Cartosat 3 satellite and 13 nanosatellite secondary payloads. Credit: ISRO

The PSLV’s second stage engine will switch off and fall away from the rocket’s third stage at T+plus 4 minutes, 25 seconds. One second later, the PSLV’s solid-fueled third stage motor will ignite to continue the mission into orbit.

Two thrusters on the PSLV’s PS4 fourth stage will ignite at T+plus 8 minutes, 23 seconds, for an eight-and-a-half minute firing to inject the mission’s 14 satellite payloads into a 316-mile-high (509-kilometer) orbit inclined 97.5 degrees to the equator.

The 3,582-pound (1,625-kilogram) Cartosat 3 satellite will separate from the PSLV’s fourth stage at T+plus 17 minutes, 42 seconds, followed by the deployment of the mission’s other 13 payloads over the next nine minutes.

Twelve of the secondary passengers set to ride the PSLV into space are owned by Planet, a San Francisco-based company that operates more than 100 shoebox-sized “Dove” CubeSats with Earth-imaging cameras. Planet, which builds its own spacecraft, says the 12 satellites launching on the PSLV are part of an upgraded series of Earth-observing nanosatellites called “SuperDoves.”

“New sensors are enabling higher image quality with sharper, more vibrant colors and accurate surface reflectance values for advanced algorithms and time-series analysis,” Planet said last month when the company announced the new SuperDove capabilities.

The SuperDove satellites will join 26 SuperDove prototypes already in orbit, according to Planet.

Planet sells 3-meter (10-foot) resolution imagery from its Dove satellites through a service named PlanetScope. The company’s large fleet of small, relatively inexpensive satellites can provide global images refreshed daily, enabling customers ranging from farmers to the U.S. government’s spy agencies to look for day-to-day changes.

The new SuperDove satellites will allow Planet to collect imagery in four, five and eight spectral bands, yielding up to five times more data than the earlier Dove satellites, according to Will Marshall, Planet’s founder and CEO. The upgrades are particularly useful for agricultural and pollution monitoring.

One of Planet’s SuperDove prototype satellites launched in late 2018 captured this view of San Francisco. Credit: Planet

Planet has launched nearly 400 satellites to date.

Sarah Bates, a Planet spokesperson, said Monday that the company currently has roughly 120 operational Dove nanosatellites in orbit. Planet has also launched larger refrigerator-sized 15 SkySat satellites, which offer higher-resolution imagery than the Dove CubeSats, and the company inherited five satellites from RapidEye when it acquired that company in 2013.

In addition to more SuperDove CubeSats, Planet has six more SkySat satellites in production and plans to launch them within the next year, Bates said.

A three-unit CubeSat named Meshbed is also riding India’s PSLV into orbit. The Meshbed nanosatellite, owned by Analytical Space of Cambridge, Massachusetts, will test an experimental phased array antenna developed by MITRE, a not-for-profit company that works with U.S. government research centers to develop innovations in defense and intelligence, aviation, health care and cybersecurity applications, among other areas.

MITRE’s patented Frequency-scaled Ultra-wide Spectrum Element, or FUSE, antenna could help enable the faster relay of satellite data to ground users, according to Analytical Space. The demonstration of the FUSE antenna, which MITRE developed in partnership with the Naval Research Laboratory, could also aid future U.S. government satellite missions in tactical communication and reconnaissance, officials said.

Built with 3D-printed parts, the FUSE antenna will unfurl from the Meshbed CubeSat after launch, then begin a series of data relay demonstrations.

“By solving the problem of fitting a wideband antenna into a CubeSat and demonstrating that it can operate in the harsh space environment, FUSE will accelerate the development of high-performance and multi-function systems, with a wide range of applications that includes military use and commercial satellite communications,” Analytical Space said.

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Follow Stephen Clark on Twitter: @StephenClark1.


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